A cylindrical lock and key set with an electronic interlock circuit includes a self-destruct circuit portion which is intercepted, engaged and destructed by an intercept member when the cylinder is forcibly, axially removed from the lock sleeve. A second intercept member may engage the circuit and destruct...http://www.google.com.hk/patents/US5186031?utm_source=gb-gplus-share專利 US5186031 - Self-destruct electrical interlock for cylinder lock and key set
